\(2Na+2HCl\rightarrow2NaCl+H_2\uparrow\)
\(Fe+2HCl\rightarrow FeCl_2+H_2\uparrow\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\uparrow\)
\(2R_x+2xHCl\rightarrow2RCl_x+xH_2\uparrow\)
\(2Na+H_2SO_4\rightarrow Na_2SO_4+H_2\uparrow\)
\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\uparrow\)
\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)
\(2R_x+xH_2SO_4\rightarrow R_2\left(SO_4\right)_x+xH_2\uparrow\)